1. Field of the Invention
The present invention relates to an interrogating device based on a forward inference system or a backward inference system.
2. Description of the Related Art
In conventional interrogating devices, the priority of rules is determined beforehand and cannot be changed during the course of execution of an inference. Therefore, in order to solve the problem in which the priority of the rules changes dynamically, there is provided a special fact for use in controlling the change of the priority other than the ordinary fact so that the priority can be apparently changed. Also, although the deletion of the rules can be carried at a command level relative to the interrogating device, the detection cannot be carried out at an action level of the rules. Accordingly, where there is a rule which is used only under a special case, as is the case with the change of the priority of the rules as hereinabove described, a special fact for use in controlling the deletion of the rules is provided so that the rules can be apparently deleted. Because of this reason, the rules can be deleted at the time of executing a rule debug. However, once the rules are deleted they cannot be restored.
As hereinabove discussed, in the conventional art interrogating device, because the special facts for use in controlling the change of the priority and in controlling the deletion of the rules are required other than the ordinary facts so that, during the execution of the inference, the priority of the rules can be changed and the rules can be deleted, respectively, the device tends to be complicated. Because the rules cannot be restored once they are deleted the rules have to be prepared from the beginning where the inference is desired to be executed by using the rules which have been deleted. Also, in the interrogating device in which both the forward inference and the backward inference are employed, neither is available for the priority of the rules of the forward inference to be superseded by the rule of the backward inference so that the deletion and restoration of the rules can be accomplished.